Loans and Leases - Non-Performing Loans and Leases (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	$ 23,974	$ 32,132
Accruing Troubled Debt Restructured Loans and Lease Modifications	14,106	13,457
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	1,954	441
Total Non-Performing Loans and Leases	40,034	46,030
Commercial, financial and agricultural [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	3,778	2,842
Accruing Troubled Debt Restructured Loans and Lease Modifications	1,406	480
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	300
Total Non-Performing Loans and Leases	5,484	3,322
Real estate-commercial real estate [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	9,858	14,340
Accruing Troubled Debt Restructured Loans and Lease Modifications	10,499	10,523
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	641
Total Non-Performing Loans and Leases	20,998	24,863
Real estate-construction [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	9,165	13,588
Accruing Troubled Debt Restructured Loans and Lease Modifications	2,164	2,397
Loans and Leases Greater than 90 Days Past Due and Accruing Interest
Total Non-Performing Loans and Leases	11,329	15,985
Real estate-residential secured for business purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	226	172
Accruing Troubled Debt Restructured Loans and Lease Modifications
Loans and Leases Greater than 90 Days Past Due and Accruing Interest
Total Non-Performing Loans and Leases	226	172
Real estate-residential secured for personal purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	720	804
Accruing Troubled Debt Restructured Loans and Lease Modifications
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	619
Total Non-Performing Loans and Leases	1,339	804
Real estate-home equity secured for personal purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases
Accruing Troubled Debt Restructured Loans and Lease Modifications
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	51	54
Total Non-Performing Loans and Leases	51	54
Loans to individuals [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases
Accruing Troubled Debt Restructured Loans and Lease Modifications	37	38
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	299	347
Total Non-Performing Loans and Leases	336	385
Lease financings [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	227	386
Accruing Troubled Debt Restructured Loans and Lease Modifications		19
Loans and Leases Greater than 90 Days Past Due and Accruing Interest	44	40
Total Non-Performing Loans and Leases	$ 271	$ 445